1. Technical Field of the Invention
The present invention generally relates to access networks that incorporate Ethernet aggregation. More particularly, and not by way of any limitation, the present invention is directed to a system and method for monitoring end nodes using Ethernet Connectivity Fault Management (CFM) functionality.
2. Description of Related Art
Current first/last mile access network solutions have significant shortcomings from subscribers' perspective, ranging from performance bottlenecks, fixed bandwidth provisioning, limited scalability, lack of flexibility and provisioning complexity to end-to-end quality of service (QoS) issues and a high cost structure. Application of robust, simple Ethernet technology in the first mile promises to revolutionize the access network as it did in the arena of enterprise networks where it started out as a local area network (LAN) transport technology that is used to communicate between computers and networks. As an access technology, Ethernet offers three significant advantages over legacy first mile technologies: (i) future-proof transport for data, video and voice applications; (ii) cost-effective infrastructure for data services; and (iii) simple, globally accepted standard that will ensure interoperability.
In order to adapt the Ethernet technology in a carrier-grade service environment, various standards are being developed that aim to provide advanced Operations, Administration and Management (OAM) capabilities (also referred to as Ethernet Connectivity and Fault Management or Ethernet CFM) across the entire network from one end to the other end. Since the end-to-end service network environment is typically comprised of a patchwork of diverse component networks (e.g., metro access networks and core networks using a variety of technologies) that may belong to different organizations, network operators and service providers, the Ethernet CFM plane is envisioned as a hierarchically layered domain space wherein specific CFM domains (or, synonymously OAM domains) are defined corresponding to the constituent network infrastructure and provisioning. In particular, two standards, IEEE 802.1ag and ITU-T draft Recommendation Y.17ethoam, incorporated by reference herein, that are specifically concerned with end-to-end Ethernet CFM define a customer-level domain at the highest level of hierarchy, which comprises one or more provider domains (occupying an intermediate level), each of which in turn includes one or more operator domains disposed at a lower hierarchical level. By way of standardization, the CFM domain space may be partitioned into a number of levels, e.g., 8 levels, each domain corresponding to a particular level, wherein a domain is defined in terms of what are referred to as flow points. In the context of the IEEE 802 specification suite, the flow points are new entities contained in the Media Access Control (MAC) “interfaces” and “ports” as defined in related standards documentation. A port can implement multiple flow points of different types. The flow points are generally referred to as ETH flow points and bound either a “Maintenance End Point” or MEP compound function or a “Maintenance Intermediate Point” or MIP compound function. Typically, the MEP compound functions are disposed at the edge of a CFM domain whereas the MIP compound functions are disposed inside a domain and remain visible to the bounding MEP functions. A node may implement a MIP function, a MEP function, or both, depending on how the domains are configured. Accordingly, the terms “MEP node” and “MIP node” may be used to loosely define a node functionality that implements a MEP compound function and a node functionality that implements a MIP compound function, respectively, although they may be defined on one single node. Whereas MEP “nodes” are used by system administrators to initiate and monitor CFM activity (by issuing appropriate CFM frames), MIP “nodes” passively receive and respond to CFM flows initiated by MEP “nodes”.
A CFM domain having one or more MIP nodes may be bounded by a plurality of MEP nodes. In order that CFM frame flows are appropriately filtered so that they are processed only by the intended domain's nodes, the MEP/MIP population of an Ethernet CFM network is configured appropriately. For instance, in accordance with the current standards, an integer value may be provided to indicate a specific domain level of an Ethernet CFM hierarchy.
Moreover, standards are also being specified to enhance service delivery technologies, which allow provisioning of Virtual LANs (VLANs) on top of a Data Link Layer (i.e., Layer-2 or L2) Ethernet network for adding flexibility, scalability and security to the CFM network. VLANs may be defined on different levels, e.g., customer-level, provider-level, etc., and can include any number of non-intersecting CFM domains. Service frame fields preceded with a “C-”, e.g., C-VLAN ID, refers to customer-created fields. Likewise, service frame fields preceded with a “S-” (e.g., S-VLAN ID), refer to service provider-added fields. By implementing VLANs, an end-to-end Ethernet CFM network may be partitioned into a number of service instances while preserving multiple subscribers' C-VLANs, wherein the traffic in a given VLAN is invisible to end hosts belonging to a different VLAN, thus reducing the broadcast domain.
Although the Ethernet CFM architecture as currently being standardized provides an impressive framework for addressing end-to-end Ethernet Connectivity and Fault Management at any level of the hierarchy, a number of issues remain to be solved. Of particular concern is the monitoring of end nodes where access links that couple the end nodes (i.e., customer network sites) to a metro provider network may operate in a non-802.1ag environment, whereas the metro provider network may comprise an 802.1ag-compliant network.